remove Vercel AI Gateway and Vercel Sandbox (#33067)

* remove Vercel AI Gateway provider and Vercel Sandbox terminal backend

Both Vercel-hosted integrations are removed end-to-end. Users on the AI
Gateway should switch to OpenRouter or one of the other aggregators
(Nous Portal, Kilo Code). Users on the Vercel Sandbox backend should
switch to Docker, Modal, Daytona, or SSH.

What's removed:
- `plugins/model-providers/ai-gateway/` provider plugin
- `hermes_cli/vercel_auth.py` Vercel-Sandbox auth helper
- `tools/environments/vercel_sandbox.py` terminal backend
- `ai-gateway` provider wiring across auth, doctor, setup, models,
  config, status, providers, main, web_server, model_normalize, dump
- `vercel_sandbox` backend wiring across terminal_tool, file_tools,
  code_execution_tool, file_operations, approval, skills_tool,
  environments/local, credential_files, lazy_deps, prompt_builder,
  cli, gateway/run
- `AI_GATEWAY_BASE_URL` constant, `_AI_GATEWAY_HEADERS` auxiliary-client
  header set, run_agent base-URL header/reasoning special-cases
- `[vercel]` pyproject extra and `vercel`/`vercel-workers` from uv.lock
- env vars: `AI_GATEWAY_API_KEY`, `AI_GATEWAY_BASE_URL`, `VERCEL_TOKEN`,
  `VERCEL_PROJECT_ID`, `VERCEL_TEAM_ID`, `VERCEL_OIDC_TOKEN`,
  `TERMINAL_VERCEL_RUNTIME`
- Tests: deletes test_ai_gateway_models.py and
  test_vercel_sandbox_environment.py; scrubs references across 23
  surviving test files (no entire tests deleted unless they were
  dedicated to AI Gateway / Sandbox)
- Docs: provider tables, env-var reference, setup guides, security
  notes, tool config, terminal-backend tables — English plus zh-Hans
  i18n parity
- `hermes-agent` skill: provider table entry and remote-backend list

What stays (intentional):
- `popular-web-designs/templates/vercel.md` — CSS design reference,
  unrelated to Vercel-the-AI-product
- `x-vercel-id` in `stream_diag.py` headers — generic Vercel CDN
  response header, useful diag signal on any Vercel-hosted endpoint
- `vercel-labs/agent-browser` URL in browser config — lightpanda
  browser project, different OSS effort
- `userStories.json` historical contributor entry mentioning Vercel
  Sandbox — archive, not active docs

Validation:
- 1153 tests in the 22 targeted files pass (`scripts/run_tests.sh`)
- Full repo `py_compile` clean
- Live import of every touched module + invariant check (no
  `ai-gateway` in `PROVIDER_REGISTRY`, no `_AI_GATEWAY_HEADERS`, no
  `vercel_sandbox` in `_REMOTE_TERMINAL_BACKENDS`)

* test: convert profile-count check from change-detector to invariant

The hardcoded "== 34" assertion broke when ai-gateway was removed.
Per AGENTS.md change-detector-test guidance, assert the relationship
(registry count >= number of plugin dirs) instead of a literal count.
Counts shift when providers are added/removed; that's expected.

website/docs/reference/cli-commands.md

@@ -95,7 +95,7 @@ Common options:
 | `-q`, `--query "..."` | One-shot, non-interactive prompt. |
 | `-m`, `--model <model>` | Override the model for this run. |
 | `-t`, `--toolsets <csv>` | Enable a comma-separated set of toolsets. |
-| `--provider <provider>` | Force a provider: `auto`, `openrouter`, `nous`, `openai-codex`, `copilot-acp`, `copilot`, `anthropic`, `gemini`, `google-gemini-cli`, `huggingface`, `novita`, `zai`, `kimi-coding`, `kimi-coding-cn`, `minimax`, `minimax-cn`, `minimax-oauth`, `kilocode`, `xiaomi`, `arcee`, `gmi`, `alibaba`, `alibaba-coding-plan` (alias `alibaba_coding`), `deepseek`, `nvidia`, `ollama-cloud`, `xai` (alias `grok`), `xai-oauth` (alias `grok-oauth`), `qwen-oauth`, `bedrock`, `opencode-zen`, `opencode-go`, `ai-gateway`, `azure-foundry`, `lmstudio`, `stepfun`, `tencent-tokenhub` (alias `tencent`, `tokenhub`). |
+| `--provider <provider>` | Force a provider: `auto`, `openrouter`, `nous`, `openai-codex`, `copilot-acp`, `copilot`, `anthropic`, `gemini`, `google-gemini-cli`, `huggingface`, `novita`, `zai`, `kimi-coding`, `kimi-coding-cn`, `minimax`, `minimax-cn`, `minimax-oauth`, `kilocode`, `xiaomi`, `arcee`, `gmi`, `alibaba`, `alibaba-coding-plan` (alias `alibaba_coding`), `deepseek`, `nvidia`, `ollama-cloud`, `xai` (alias `grok`), `xai-oauth` (alias `grok-oauth`), `qwen-oauth`, `bedrock`, `opencode-zen`, `opencode-go`, `azure-foundry`, `lmstudio`, `stepfun`, `tencent-tokenhub` (alias `tencent`, `tokenhub`). |
 | `-s`, `--skills <name>` | Preload one or more skills for the session (can be repeated or comma-separated). |
 | `-v`, `--verbose` | Verbose output. |
 | `-Q`, `--quiet` | Programmatic mode: suppress banner/spinner/tool previews. |

website/docs/reference/environment-variables.md

@@ -18,8 +18,6 @@ All variables go in `~/.hermes/.env`. You can also set them with `hermes config
 | `HERMES_OPENROUTER_CACHE_TTL` | Cache TTL in seconds (1-86400). Overrides `openrouter.response_cache_ttl` in config.yaml. |
 | `NOUS_BASE_URL` | Override Nous Portal base URL (rarely needed; development/testing only) |
 | `NOUS_INFERENCE_BASE_URL` | Override Nous inference endpoint directly |
-| `AI_GATEWAY_API_KEY` | Vercel AI Gateway API key ([ai-gateway.vercel.sh](https://ai-gateway.vercel.sh)) |
-| `AI_GATEWAY_BASE_URL` | Override AI Gateway base URL (default: `https://ai-gateway.vercel.sh/v1`) |
 | `OPENAI_API_KEY` | API key for custom OpenAI-compatible endpoints (used with `OPENAI_BASE_URL`) |
 | `OPENAI_BASE_URL` | Base URL for custom endpoint (VLLM, SGLang, etc.) |
 | `COPILOT_GITHUB_TOKEN` | GitHub token for Copilot API — first priority (OAuth `gho_*` or fine-grained PAT `github_pat_*`; classic PATs `ghp_*` are **not supported**) |
@@ -156,10 +154,6 @@ For native Anthropic auth, Hermes prefers Claude Code's own credential files whe
 | `HINDSIGHT_TIMEOUT` | Timeout in seconds for Hindsight memory-provider API calls (default: `60`). Bump this if your Hindsight instance is slow to respond during `/sync` or `on_session_switch` and you're seeing timeouts in `errors.log`. |
 | `SUPERMEMORY_API_KEY` | Semantic long-term memory with profile recall and session ingest ([supermemory.ai](https://supermemory.ai)) |
 | `DAYTONA_API_KEY` | Daytona cloud sandboxes ([daytona.io](https://daytona.io/)) |
-| `VERCEL_TOKEN` | Vercel Sandbox access token ([vercel.com](https://vercel.com/)) |
-| `VERCEL_PROJECT_ID` | Vercel project ID (required with `VERCEL_TOKEN`) |
-| `VERCEL_TEAM_ID` | Vercel team ID (required with `VERCEL_TOKEN`) |
-| `VERCEL_OIDC_TOKEN` | Vercel short-lived OIDC token (development-only alternative) |
 
 ### Langfuse Observability
 
@@ -192,7 +186,7 @@ These variables configure the [Tool Gateway](/user-guide/features/tool-gateway)
 
 | Variable | Description |
 |----------|-------------|
-| `TERMINAL_ENV` | Backend: `local`, `docker`, `ssh`, `singularity`, `modal`, `daytona`, `vercel_sandbox` |
+| `TERMINAL_ENV` | Backend: `local`, `docker`, `ssh`, `singularity`, `modal`, `daytona` |
 | `HERMES_DOCKER_BINARY` | Override the container binary Hermes shells out to (e.g. `podman`, `/usr/local/bin/docker`). When unset, Hermes auto-discovers `docker` or `podman` on `PATH`. Needed when both are installed and you want the non-default, or when the binary lives outside `PATH`. |
 | `TERMINAL_DOCKER_IMAGE` | Docker image (default: `nikolaik/python-nodejs:python3.11-nodejs20`) |
 | `TERMINAL_DOCKER_FORWARD_ENV` | JSON array of env var names to explicitly forward into Docker terminal sessions. Note: skill-declared `required_environment_variables` are forwarded automatically — you only need this for vars not declared by any skill. |
@@ -201,7 +195,6 @@ These variables configure the [Tool Gateway](/user-guide/features/tool-gateway)
 | `TERMINAL_SINGULARITY_IMAGE` | Singularity image or `.sif` path |
 | `TERMINAL_MODAL_IMAGE` | Modal container image |
 | `TERMINAL_DAYTONA_IMAGE` | Daytona sandbox image |
-| `TERMINAL_VERCEL_RUNTIME` | Vercel Sandbox runtime (`node24`, `node22`, `python3.13`) |
 | `TERMINAL_TIMEOUT` | Command timeout in seconds |
 | `TERMINAL_LIFETIME_SECONDS` | Max lifetime for terminal sessions in seconds |
 | `TERMINAL_CWD` | Working directory for terminal sessions (gateway/cron only; CLI uses launch dir) |